Blind stitch sewing machine



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BLIND STITCH SEWING MACHINE Fi1e d`Jan. 1e, 193e 5 shets-sneet 5 Patented Mar. 23, 1937 UNITED STATES PATENT orties BLIND STITCH SEWING MACHINE Application January 16, 1936, Serial No. 59,456

5 Claims.

This invention relates to new and useful improvements in blind stitch sewing machines generally, although more particularly to blind stitch sewing machines employed in hemming opera- 5 tions.

The principal object of the invention is to provide a blind stitch sewing machine of the double thread chain stitch type for seaming hems, by means of which a line of stitches will be formed l to unite the hem fold to the body fabric, the

connecting portions of the needle thread between adjacent needle loops being positioned in a straight line in parallelism with the inner edge of the hem and the enchained looper thread loops l being disposed under the inner edge of the hem and thereby concealed from View.

Another important object of my invention lies in the provision of a threaded 4-motion reciprocatory looper which cooperates with a needle mounted for reciprocation across the line of feed, the looper 'having a path of travel in a single straight line in the line of feed and being located entirely on that side of the ridge forming element opposite the point of needle penetration in the fabric, whereby the feed of the fabric and the rearward stroke of the needle will effect the opening of the looper thread loop for entrance by the needle.

With these and other objects in View which will more fully appear, the nature of the invention will be more clearly understood by following the description, the appended claims, and the several views illustrated in the accompanying drawings.

In the drawings:

Figure 1 is a top` plan view of a sewing machine constructed in accordance with my invention7 Figure 2 is a left hand elevation thereof, the base being omitted,

Figure 3 is a front View of the stitching mechanism and the work presenting means,

Figure 4 is a partial rear end elevation partly in section showing the driving connections between the main shaft and the 4-motion top feed, and between the main shaft and the looper,

Figure 5 is a bottom plan view of the forwardly extending arm showing particularly the presser foot, the looper mechanism, and the top feed mechanism,

Figure 6 is a detail elevation of the top feed mechanism, the view showing particularly the means for imparting the up and down and the back and forth movements to the feed dog,

Figure `7 is a detail view showing the mechanism for imparting the needle-avoiding movements to the looper,

Figure 8 is an enlarged view of the presser foot, the needle, and the fabric being hemmed, the view showing the looper at the rear end of its stroke and the needle at the forward end of its stroke,

Figure 9 is a similar view but showing the looper moving forwardly through th-e needle thread loop, Y

Figure 10l is a similar view but showing the looper at the forward end of its stroke and the needle at the end of its backward stroke,

Figure 11 is a similar view but showing the looper being moved rearwardly and the needle in a position about to enter the looper thread loop,

Figure 12 is a top plan view of the presser foot,

Figure 13 is an enlarged View showing a hem seamed by my invention, and

Figure 14 is a detail view of the looper.

Like reference numerals designate corresponding parts throughout the several figures of the drawings.

My invention is adapted especially for joining a hem A to a body fabric or base layer B by a line of blind stitches, as shown in Figure 13. The inner edge of the hemA is indicated at a, and the hem may have an inturned edge portion a. if desired. A needle thread C and a looper thread D are employed to form a line of Grover and Baker stitches, which are otherwise known as double-lock and double-chain stitches. The stitches include needle thread loops c which are spaced equidistantly apart and pass downwardly through the hem at points c', the connecting portions of the thread between the loops being arranged in a straight line and in parallelism to the inner edge a, of the hem. Certain of these needle loops enter and emerge from the upper face of the body fabric as indicated at c2 to thereby form anchor stitches E which function to join the hem with the body fabric, while other needle loops miss the body fabric` entirely to thereby form resultant skip stitches F. rIhe enchained loops d of the looper thread which are concatenated with the needle loops c, are all located between the hem and the body fabric and are consequently concealed from view by the hem. It will be understood, however, that all anchor stitches, or alternate anchor and skip stitches, or any combination thereof, may be employed. l The machine of my invention includes a base` 5 having a standard 6 projecting upwardly from the rear right hand 'corner thereof, an arm 1 which extends laterally from the upper end of said standard, and an arm 8 which extends forwardly from the left hand end of the arm 1. Fixed to the free end of the arm 8 in the usual manner is a horizontal presser foot 9 having a centrally located and longitudinally extending opening I0 formed therein. Journaled in the laterally extending arm 1 is a main shaft II and journaled in the arm 8 is an oscillatory needle shaft I2 which A is driven from the main shaft by a connection indicated generally at I3. The needle shaft I 2 is disposed directly above the opening I0 in the foot, and fixed to the outer end of the shaft is a needle arm I4 carrying a curved needle I5. Thus when the needle shaft I2 is oscillated the needle I5 will reciprocate transversely across the opening I0 in the presser foot. It willbe noted at this time that the penetrating stroke of the needle I5, as viewed from the front of the machine, is from right to left.

Rigid with the base 5 are posts I6 which are located in a plane in advance of the standard 6 and pivotally supported on the upper ends of these posts is a work support I1 having a lateral extension I8 which projects under the presser foot 8 the work support I1 being yieldably held against depression by a spring (not shown). The upward movement of the work support is adjustably limited by a stop I9 mounted on the work support I1 and cooperating with the machine frame as shown in the Mueller Patent 2,018,186, Oct. 22, 1935.

As previously stated this machine is particularly intended for hemming operations and to this end means are provided for projecting a ridge of material upwardly through the presser foot opening I0 into needle penetrating position during each cycle. For this purpose, I have provided a vertically reciprocatory ridge forming element or plunger 20 which is located below the presser foot opening I0 and in a vertical plane containing the path of needle oscillation. The plunger 28 is attached to the upper end of a vertically reciprocatory cam plate 2l which is slidably mounted in the extension I8 of the work support. The cam plate 2I is raised and lowered by a co-operating cam 22 which is fixed to a rock shaft 23 which is journaled in bearings on the underside of the work support I1. The rock shaft 23 is oscillated from the main shaft II by connections which are not shown but which are similar to those shown in the Mueller Patent 2,018,186 above referred to, said connections functioning to raise the plunger 20 higher during alternate cycles whereby alternate anchor and skip stitches will be formed in the hem.

A vertically yieldable work clamp 24 is mounted on the lateral extension I8 of the work support I1 and cooperates with the lower face of the presser foot 9 in the usual manner to clamp the fabric against the thrust of the needle.

A top feeding mechanism for feeding the material rearwardly up to and past the needle lncludes a 4-motion feed dog 25 having a front feed section 26 and a rearwardly spaced feed section 21, said sections being connected by a longitudinally extending bridge 28 forming a resultant opening 29 thereunder. This feed dog 25 is attached to a feed bar 30 by screws 3|. The feed sections operate in the opening I0 of the presser foot and against the upwardly spring pressed work clamp 24, the front section 26 being'located in front of the needle path and the rear section 21 in rear of said path. The feed bar 3U is raised and lowered by a train of mechanism from the main shaft I I, and is moved back and forth by a train of mechanism operated from said main shaft. A bell crank lever 32 is pivoted at its angle as at 33 to the forwardly extending arm 8 of the frame. This bell crank lever includes a forwardly extending arm 34 and a downwardly extending arm 35. A link 36 is pivotally connected at its upper end as at 31 to the arm 34 and at its lower end as at 38 to the feed bar 30. The rear end of the feed bar is provided with an open ended slot 39 which has sliding connection on a bearing pin 40 fixed to the forwardly extending frame arm 8. A pitman 4I is pivotally connected at its forward end as at 42 to the depending arm 35 of the bell crank lever 32 and the rear end of this pitman is connected with an eccentric 43 fixed on the main shaft I I. It will thus be seen that upon rotation of the main shaft, the eccentric 43 will rock the bell crank lever 32 which, through the medium of the link 36, will raise and lower the feed bar 38. In order to move the feed bar back and forth, I have provided a slotted segment 44 which is pivoted at its upper end as at 45 to the forwardly extending frame arm 8. A driving link 46 is pivotally connected at its forward end as at 41 to the feed bar 30 and the rear end of this link is adjustably connected to the slotted segment 44 by a clamping bolt 48, the slot of the segment being arcuate and having for its center the pivot 41. The slotted segment 44 is pivotally connected as at 49 to a sleeve 50 which surrounds an eccentric 5I fixed on the main shaft I I. Thus upon rotation of the main shaft II, the eccentric 5I will impart swinging movements to the slotted segment 44 and this segment through the medium of the link 46 will impart back and forth movements to the feed bar 30. By adjusting the clamping bolt 48 lengthwise of the slotted segment 44 the length of feed travel imparted to the feed dog 25 may be readily Varied.

Cooperating with the needle is a hook-shaped looper 52 which is threaded with the looper thread D. This looper includes a forwardly extending beak 53 having a thread eye 53a at its forward end, a forwardly extending neck 54 which overlies the beak and is provided with a thread eye 55, and an upwardly extending shank 56, the beak, the neck and the shank being all disposed in the same vertical plane. A longitudinal groove 53b is formed in the underside of the beak and communicates with the thread eyes 53a and 55. The looper extends in the line of feed, and means are provided for imparting to the looper a forward and backward motion and an up and down or needle-avoiding motion. To this end, a lever 51 extends longitudinally within the frame arm 8 and is pivoted intermediate its ends thereto, as at 58. The rear end of the lever is provided with a fork 59 which embraces an eccentric 60 fixed on the end of the main shaft II. The forward end of the lever is provided with an upstanding arm 6I which carries at its upper end a horizontal bearing pin 62. An inverted U-shaped rocking frame 63 straddles the upstanding arm 6I and is fulcrumed at its upper end on the pin 62. The shank 56 of the looper is attached to the lower end of the arm 64 of said rock frame by a screw 65. A link 66 is pivotally connected at its forward end as at 61 to the lower end of the other arm 68 of said rocking frame, and at its rear end to an eccentric pin 69 fixed to the eccentric 60. Thus, the lever 51 imparts up and down or needle-avoiding move- Gil,

ments to the looper, and the link 66 imparts forward and backward movements to the looper, the eccentric pin 69 being located on the eccentric iil in such timed relation thereto that the component of the two movements results in an elliptical or Li-motion path of travel being imparted to the looper.

It will be noted that the looper in its needleloop penetrating movement travels forwardly or in a direction opposite the direction of feed; that the looper passes over the needle when entering the needle thread loop; that the looper during the backward stroke thereof passes under the needle path to permit the needle to enter the looper thread loop; that the looper path of travel in its loop taking movement and also in its loop shedding movement is in a single straight line in the line of feed in each movement and is located entirely on that side of the ridge forming element opposite the point of needle penetration in the fabric, whereby the feed of the fabric and the rearward stroke of the needle will effect the opening of the looper thread loop for entrance by the i needle; that the needle I5 has its path of movement across the line of feed and under the bridge 23 of the feed dog; that the front feed section 2G functions to feed the fabric up to the needle and the rear section 2l functions to feed the fabric rearwardly away from the needle; that the feed dog 25 operates in the vertical plane of the ridgeforming plunger 20 and that the feed sections 26, 2l are disposed in front of and in rear of said plunger, and that the feed dog cooperates with the vertically yieldable work clamp 24 through the presser foot opening I 0. i

v A spring plate 1D is mounted on the presser foot 9 at the forward end thereof and under the bridge 28 of the feed dog. The free end of the plate projects into the presser foot opening Il] above the plunger 20 and cooperates with the latter to retain the fabric against the thrust of the needle. It is of course to be understood that the details of structure and arrangement of parts may be 1 variously changed and modified without departing from the spirit and scope of my invention.

I claim:

1. In a sewing machine stitch forming mechanism, the combination with a feeding mechanism, of a threaded needle mounted for reciprocations across the line of feed, a lever fulcrumed to swing about an axis transverse to the line of feed, a looper carrier pivoted to one end of the lever to swing about an axis transverse to the line of .j feed, a threaded looper mounted on said carrier,

means to oscillate said lever to impart needleavoiding movements to the looper, and means for oscillating the looper carrier to impart backward and forward movements to the looper.

2. In a sewing machine stitch forming mechanism, the combination with a feeding mechanism, of a threaded needle mounted for reciprocations across the line of feed, a lever fulcrumed to swing about an axis transverse to the line of feed, a

f looper carrier pivoted to one end of the lever to swing about an axis transverse to the line of feed, a threaded looper mounted on said carrier, means to oscillate said lever to impart needleavoiding movements to the looper, and means for oscillating the looper carrier to impart backward and forward movements to the looper, the looper in its forward travel moving in a direction opposite the direction of feed and passing above the needle, and in its backward travel passing below the needle.

3. In a sewing machine, the combination with a frame including a forwardly extending arm, of a horizontal presser foot fixed to the front end of said arm and having an opening, a main shaf journaled in the rear of said arm, a needle shaft extending longitudinally of and journaled in said arm, a needle mounted on said needle shaft for reciprocations across the opening in the foot, driving connections between the main shaft and the needle shaft, a lever extending longitudinally lof the arm and fulcrumed intermediate its ends on said arm, a looper carrier pivoted on the front end of said lever to swing back and forth in the line of feed and above the foot, a threaded looper mounted on said carrier, connections between the main shaft and the lever for imparting up and down needle-avoiding movements to the looper, and connections between the main shaft and the carrier for imparting backward and forward movements to the looper.

4. In a sewing machine, the combination with a frame including a forwardly extending arm, of a horizontal presser foot xed to the front end of said arm and having an opening, a main shaft journaled in the rear of said arm, a needle shaft extending longitudinally of and journaled in said arm, a needle mounted on said needle shaft for reciprocations across the opening in the foot, driving connections between the main shaft and the needle shaft, a lever extending longitudinally of the arm and fulcrumed intermediate its ends on said arm, the rear end of the lever being forked, a looper carrier pivoted on the front end of said lever to swing back and forth in the line of feed and above the foot, a threaded looper mounted on said carrier, an eccentric fixed to the main shaft and engageable with the fork of the lever for imparting up and down needle-avoiding movements to the looper, an eccentric pin fixed to the eccentric, and a link connecting the looper carrier and the eccentric pin for imparting backward and forward movements to the looper.

5. In a sewing machine, the combination with a frame including a forwardly extending arm, of a horizontal presser foot fixed to the front end of said arm and having an opening, a main shaft journaled in the rear of said arm, a needle shaft extending longitudinally of and journaled in said arm, a needle mounted on said needle shaft for reciprocations across the opening in the foot, driving connections between the main shaft and the needle shaft, a lever extending longitudinallyof the arm and fulcrumed intermediate its ends on said arm, an inverted U-shaped looper carrier straddling the forward end of the lever, a horizontal pivot connecting the lever and the upper end of the carrier, a threaded looper mounted on the lower end of one leg of the carrier, connections between-the main shaft and the lever for imparting up and down needle-avoiding movements to the looper, and connections between the main shaft and the other leg of the carrier for imparting backward and forward movements to the looper in the line of feed.

JOSEPH MANN. 

